What happens to the concentration of reactants and products at equilibrium?

At equilibrium, the system has reached a state where the rates of the forward and reverse reactions are equal. This means that the concentrations of the reactants and products remain constant over time, even though the reactions continue to occur at a molecular level. Since the rates are balanced, there is no net change in the concentration of either reactants or products, leading to a stable condition in the system.

In contrast, during the progression toward equilibrium, the concentrations of reactants may decrease as they are converted to products, while the concentrations of products may increase. However, once equilibrium is achieved, these changes cease, resulting in constant concentrations. This principle is a fundamental aspect of chemical equilibrium and is described by Le Chatelier's Principle, which asserts that a system at equilibrium will respond to disturbances in a way that counteracts the change, reinforcing the idea that concentrations remain stable.

Understanding this concept is crucial for predicting how changes in conditions, such as concentration, pressure, and temperature, can affect the position of equilibrium but does not alter the fact that concentrations are constant at equilibrium itself.